Kivisalmi pumping station improves water quality and affects ice conditions

Kivisalmi pumping station improves water quality and affects ice conditions

The pumping station in Kivisalmi has been in operation for slightly over a year now. The pump has worked flawlessly and water quality has improved significantly. The flow affects the ice conditions, extensively weakening the ice in the mid-lake area of Piiluvanselkä.
The effects of the Kivisalmi pumping station and the water quality have been monitored for a year, now, at four sampling points, at first every two weeks and later once a month. The results from the one-year sampling period are very promising.

The best results were observed in the reduction of nutrient concentrations. Especially phosphorus concentration has been significantly reduced in the mid-lake areas of Piiluvanselkä and Sunisenselkä. From among the primary nutrients, phosphorus is the most significant algal growth regulator.

COD (chemical oxygen demand), which expresses the amount of organic compounds in the water, has remained steady. The NTU (nephelometric turbidity unit) of the water, i.e. its brown colour, has increased slightly. On the other hand, turbidity has decreased, i.e. the water is clearer.

All concentrations are typically at their highest during open water season. Under the ice in winter, nutrient concentrations and turbidity, in particular, are at their lowest. Due to stratification, concentrations are usually higher in the bottom water near the lakebed. This could be seen most clearly in the mid-lake areas of Vehkasalonselkä and Jakaranselkä. Stratification was weak in the mid-lake areas of Sunisenselkä and Piiluvanselkä, and concentrations had less variation between different depths.

The flow of water caused by the pumping station weakens the ice. The water flows from Kivisalmi towards Sunisenselkä. At present, the melted area stretches midway between the islands of Ruohosaari and Voisalmensaari in the shape of a wide crack. Of course the area where the ice has weakened is wider than the crack and therefore also more treacherous, because the thickness of the ice cannot be estimated from the surface. Mild weather makes the ice melt faster, widening the area of weak ice.

Buoys are placed on the ice and signs are put up on the beach to warn about weak ice. The Lappeenranta Region Environmental Office urges everyone who goes on the ice to use extreme caution. Old familiar routes are not safe anymore.

For more information, please contact:

Lappeenranta Region Environmental Office
Raija Aura, +358 40 5843 278
Ilkka Räsänen, +358 400 815 284